package NC72_二叉树的镜像;

import java.util.*;

class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;
    }
}

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param pRoot TreeNode类
     * @return TreeNode类
     */
    public TreeNode Mirror (TreeNode pRoot) {
        // write code here
        if (pRoot == null){
            return null;
        }
        if (pRoot.left == null && pRoot.right == null){
            return pRoot;
        }

        // 处理根节点，交换左右节点
        TreeNode temp = pRoot.left;
        pRoot.left = pRoot.right;
        pRoot.right = temp;

        // 处理左子树
        Mirror(pRoot.left);
        // 处理右子树
        Mirror(pRoot.right);

        return pRoot;
    }
}